Environmentalists warn that the world cannot continue to support an ever-increasing population. Resources are finite, and they are starting to run out, or will run out soon.
Perhaps the most important resource is food. The consequences of running out of food are surely more dire than running out of almost any other resource. So let's take a look at the present state and future prospects of the world's food supply.
Thomas Malthus wrote one of the first books advocating population control, in 1798. It bore the catchy title, An Essay on the Principle of Population as it Affects the Future Improvement of Society. He analyzed the situation as follows: Population grows expoentially. That is, it grows by some percentage of the current population every year. So as the population gets bigger, it grows faster, which means that the next year it is bigger still, growing faster and faster. But food production is limited by available land, water for irrigation, and so on. These things are finite. At best food production might grow linearly, that is, increase by the same amount every year. But eventually even that rate of growth will be impossible to maintain, as available land, water, etc are used up, and increases in food production must start to taper off. Thus, with the number of people growing faster and faster, and food production growing slower and slower, sooner or later it will simply be impossible to feed all the people, and there will be mass starvation.
In Malthus time the population of Britain (Malthus home country) was about 11 million, which he considered the country was just barely able to feed. He wrote that the idea that the nation could feed double this number, or 22 million, was "probably a greater increase than could with reason be expected". To support double this again, or 44 million, would be "impossible to suppose", and that this impossibility "must be evident to those who have the slightest acquantance with agricultural subjects". (An Essay on the Principle of Population as it Affects the Future Improvement of Society, Thomas Malthus, 1798.)
Britain today has a population of over 68 million (UK Population), who do not appear to be starving.
What was wrong with Malthus analysis?
He was fairly close about population growth: it does indeed tend to increase exponentially. In recent decades it has been increasing more slowly than Malthus would have predicted. This graph shows actual population growth from 1962 to 2020. (World Population by Year) (I chose that date range simply because it was the date range I happened to be able to find data for when writing this article.) I then compare this to what Malthus would have predicted using his formulas, based on the data for 1960 to 1970. That is, If we assume that Malthus formula would be right for 1960 to 1970, what would that same formula yield for 1970 to 2020? (To be fair to Malthus here, let me make clear that Malthus doesn't give numerical predictions for the 21st century in his paper. I'm extrapolating from his numbers.)
World Population:
Malthus Predictions vs. Actual
(Millions of people)
Now let's look at food production. Here's a graph of total world food production, using data from the United Nations Food and Agriculture Organization.
World Food Production:
Malthus Predictions vs. Actual
(Index: 2014-2016=100)
Malthus said that the best that one could hope was that food production would increase linearly. So to give Malthus the overwhelming benefit of the doubt, I take production from 1962 to 1982 and extrapolate that forward to 2020. (If you're into technical details, I did a least-squares linear regression on the data for 1962 to 1982, which gives y=.92x-27. Then plot this line from 1962 to 2020. If you don't follow the math of that, just look at the graph and I think you'll see that the "linear" line follows the "actual" very closely from 1962 to 1982, and then continues in a straight line from there.)
But, Malthus said, even a linear increase is more than could realistically be hoped for. He didn't give a formula for what increase he thought would be plausible, but my "Malthus" line here is linear for 1962 to 1982 and then gradually tapers off. One could quibble about how fast it should taper off, but in any case it would be below the "linear" line.
Simply put, Malthus was completely wrong about food production. Actual food production did not increase more and more slowly. It did not even increase merely linearly. It increased faster and faster.
Environmentalists today admit that Malthus was overly pessismistic, but they still hold to his basic ideas. They continue to warn that the disaster is almost upon us. Occassionally some will even say that it is already beginning. For example, Paul Ehrlich, one of the leading population control advocates, wrote in the 1990s that "40,000 children die daily from hunger-related diseases". (The Population Explosion, Paul Ehrlich, 1990
) This comes to 14.6 million per year. He doesn't say where he got this number. Presumably most of these starvation deaths must be occurring in the developing world -- few people in the US or Europe are dying of starvation. But according to UNICEF, in the 1990s about 12.9 million children in the developing world died each year, of all causes combined. (Thankfully, the numbers have gone down since then.) Of these, UNICEF claims that 8.1 million could be prevented with proper medical care, primarily vaccines. Ehrlich claims that more children die of starvation, then in real life die of all causes combined.But as the population grows there is less and less food to go around, right? Well, let's see. Here's another graph using data from that same UN FAO web site. This one shows total world food production per person.
World Food Production Per Person
(Index: 2014-2016=100)
According to the United Nations figures, since 1962, world food production per person has increased by 45%. Note we are not saying that food production has increased by 45%, but food production per person. And even this incredible increase is surely less than what could be done. For the overwhelming majority of Americans and Europeans, the problem is not that they have too little to eat, but that they eat too much. So there is no need for food production for these people to increase.
How is it possible to continue to increase production year after year like this? For most of history, and even today in many parts of the world, the major limit on food production is the number of farmers available to work the land. As the population grows, so does the number of farmers. In addition, what's really enabled the increase of the last few decades has been the so-called "Green Revolution": irrigation, selective breeding of improved crops, and fertilizer.
Some argue that these advances have now gone as far as possible, that all that was accomplished was postponing the disaster, and that we are now once again pushing the limits. Well, it would surely be pessimistic to assume that after centuries of advances, agricultural technology is now going to stop dead. But even if it did, we could just plant more crops. The UN came out with a study back in 1970, which is a little out-of-date but there is no reason to believe things have changed much since then, on how much land in the world is suitable for agriculture. If you assume that we are not going to cut down any forests or make other major changes to the landscape, there are about 4.4 billion hectares. Of this, 1.4 billion, or less than a third, are actually being used to grow crops. (1970 Statistical Yearbook, United Nations, 1970.)
(First version posted 10 Sep 2000. Updated 20 Sept 2022.)
© 2022 by Jay Johansen
No comments yet.